About 42 percent of the state’s residents don’t go to the dentist yearly, according to one study. Two other recent studies of Mississippi children by the health department showed the rate of tooth decay is 56 percent for Head Start children and 70 percent for third-graders, Mosca said.

The health department beefed up its program in 2002 in response. Since then, 64 water companies have added fluoride, Mosca said. About 53 percent of Mississippi’s population is on fluoridated public water systems.

That number includes Itta Bena, the only water supplier in Leflore or Carroll counties with more than 2,000 customers that fluoridates.

The other local water companies that are big enough for the new rule to apply to are East Leflore Water and Sewer, Mississippi Valley State University, Vaiden and North Carrollton.

Mosca said the health department has private and public funds available to pay for equipment, although not enough for everyone in the state.

The Bower Foundation, a non-profit that supports health projects in Mississippi, pays for equipment and a year’s worth of fluoride. The health department offsets about 40 percent of that cost with federal grants.

Assuming a 15-year lifespan, the average annual cost to fluoridate is 75 cents per person, according to an economic impact statement filed by the health department.

The purpose of the new regulation was to establish rules for monitoring — which must be done at least three times per week — and give the department access to stimulus money, according to Mosca.